This commit implements the "delete" subcommand:
git reflog delete master@{2}
will delete the second reflog entry of the "master" branch.
With this, it should be easy to implement "git stash pop" everybody
seems to want these days.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>